// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (c) 2014 Google, Inc. * * Selftests for execveat(2). */ #ifndef _GNU_SOURCE#define _GNU_SOURCE  /* to get O_PATH, AT_EMPTY_PATH */#endif#include <sys/sendfile.h>#include <sys/stat.h>#include <sys/syscall.h>#include <sys/types.h>#include <sys/wait.h>#include <errno.h>#include <fcntl.h>#include <limits.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h> #include "../kselftest.h" #define TESTS_EXPECTED 54#define TEST_NAME_LEN (PATH_MAX * 4) #define CHECK_COMM "CHECK_COMM" static char longpath[2 * PATH_MAX] = "";static char *envp[] = { "IN_TEST=yes", NULL, NULL };static char *argv[] = { "execveat", "99", NULL }; static int execveat_(int fd, const char *path, char **argv, char **envp,		     int flags){#ifdef __NR_execveat	return syscall(__NR_execveat, fd, path, argv, envp, flags);#else	errno = ENOSYS;	return -1;#endif} #define check_execveat_fail(fd, path, flags, errno)	\	_check_execveat_fail(fd, path, flags, errno, #errno)static int _check_execveat_fail(int fd, const char *path, int flags,				int expected_errno, const char *errno_str){	char test_name[TEST_NAME_LEN];	int rc; 	errno = 0;	snprintf(test_name, sizeof(test_name),		 "Check failure of execveat(%d, '%s', %d) with %s",		 fd, path?:"(null)", flags, errno_str);	rc = execveat_(fd, path, argv, envp, flags); 	if (rc > 0) {		ksft_print_msg("unexpected success from execveat(2)\n");		ksft_test_result_fail("%s\n", test_name);		return 1;	}	if (errno != expected_errno) {		ksft_print_msg("expected errno %d (%s) not %d (%s)\n",			       expected_errno, strerror(expected_errno),			       errno, strerror(errno));		ksft_test_result_fail("%s\n", test_name);		return 1;	}	ksft_test_result_pass("%s\n", test_name);	return 0;} static int check_execveat_invoked_rc(int fd, const char *path, int flags,				     int expected_rc, int expected_rc2){	char test_name[TEST_NAME_LEN];	int status;	int rc;	pid_t child;	int pathlen = path ? strlen(path) : 0; 	if (pathlen > 40)		snprintf(test_name, sizeof(test_name),			 "Check success of execveat(%d, '%.20s...%s', %d)... ",			 fd, path, (path + pathlen - 20), flags);	else		snprintf(test_name, sizeof(test_name),			 "Check success of execveat(%d, '%s', %d)... ",			 fd, path?:"(null)", flags); 	child = fork();	if (child < 0) {		ksft_perror("fork() failed");		ksft_test_result_fail("%s\n", test_name);		return 1;	}	if (child == 0) {		/* Child: do execveat(). */		rc = execveat_(fd, path, argv, envp, flags);		ksft_print_msg("child execveat() failed, rc=%d errno=%d (%s)\n",			       rc, errno, strerror(errno));		exit(errno);	}	/* Parent: wait for & check child's exit status. */	rc = waitpid(child, &status, 0);	if (rc != child) {		ksft_print_msg("waitpid(%d,...) returned %d\n", child, rc);		ksft_test_result_fail("%s\n", test_name);		return 1;	}	if (!WIFEXITED(status)) {		ksft_print_msg("child %d did not exit cleanly, status=%08x\n",			       child, status);		ksft_test_result_fail("%s\n", test_name);		return 1;	}	if ((WEXITSTATUS(status) != expected_rc) &&	    (WEXITSTATUS(status) != expected_rc2)) {		ksft_print_msg("child %d exited with %d neither %d nor %d\n",			       child, WEXITSTATUS(status), expected_rc,			       expected_rc2);		ksft_test_result_fail("%s\n", test_name);		return 1;	}	ksft_test_result_pass("%s\n", test_name);	return 0;} static int check_execveat(int fd, const char *path, int flags){	return check_execveat_invoked_rc(fd, path, flags, 99, 99);} static char *concat(const char *left, const char *right){	char *result = malloc(strlen(left) + strlen(right) + 1); 	strcpy(result, left);	strcat(result, right);	return result;} static int open_or_die(const char *filename, int flags){	int fd = open(filename, flags); 	if (fd < 0)		ksft_exit_fail_msg("Failed to open '%s'; "			"check prerequisites are available\n", filename);	return fd;} static void exe_cp(const char *src, const char *dest){	int in_fd = open_or_die(src, O_RDONLY);	int out_fd = open(dest, O_RDWR|O_CREAT|O_TRUNC, 0755);	struct stat info; 	fstat(in_fd, &info);	sendfile(out_fd, in_fd, NULL, info.st_size);	close(in_fd);	close(out_fd);} #define XX_DIR_LEN 200static int check_execveat_pathmax(int root_dfd, const char *src, int is_script){	int fail = 0;	int ii, count, len;	char longname[XX_DIR_LEN + 1];	int fd; 	if (*longpath == '\0') {		/* Create a filename close to PATH_MAX in length */		char *cwd = getcwd(NULL, 0); 		if (!cwd) {			ksft_perror("Failed to getcwd()");			return 2;		}		strcpy(longpath, cwd);		strcat(longpath, "/");		memset(longname, 'x', XX_DIR_LEN - 1);		longname[XX_DIR_LEN - 1] = '/';		longname[XX_DIR_LEN] = '\0';		count = (PATH_MAX - 3 - strlen(cwd)) / XX_DIR_LEN;		for (ii = 0; ii < count; ii++) {			strcat(longpath, longname);			mkdir(longpath, 0755);		}		len = (PATH_MAX - 3 - strlen(cwd)) - (count * XX_DIR_LEN);		if (len <= 0)			len = 1;		memset(longname, 'y', len);		longname[len] = '\0';		strcat(longpath, longname);		free(cwd);	}	exe_cp(src, longpath); 	/*	 * Execute as a pre-opened file descriptor, which works whether this is	 * a script or not (because the interpreter sees a filename like	 * "/dev/fd/20").	 */	fd = open(longpath, O_RDONLY);	if (fd > 0) {		ksft_print_msg("Invoke copy of '%s' via filename of length %zu:\n",			       src, strlen(longpath));		fail += check_execveat(fd, "", AT_EMPTY_PATH);	} else {		ksft_print_msg("Failed to open length %zu filename, errno=%d (%s)\n",			       strlen(longpath), errno, strerror(errno));		fail++;	} 	/*	 * Execute as a long pathname relative to "/".  If this is a script,	 * the interpreter will launch but fail to open the script because its	 * name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.	 *	 * The failure code is usually 127 (POSIX: "If a command is not found,	 * the exit status shall be 127."), but some systems give 126 (POSIX:	 * "If the command name is found, but it is not an executable utility,	 * the exit status shall be 126."), so allow either.	 */	if (is_script) {		ksft_print_msg("Invoke script via root_dfd and relative filename\n");		fail += check_execveat_invoked_rc(root_dfd, longpath + 1, 0,						  127, 126);	} else {		ksft_print_msg("Invoke exec via root_dfd and relative filename\n");		fail += check_execveat(root_dfd, longpath + 1, 0);	} 	return fail;} static int check_execveat_comm(int fd, char *argv0, char *expected){	char buf[128], *old_env, *old_argv0;	int ret; 	snprintf(buf, sizeof(buf), CHECK_COMM "=%s", expected); 	old_env = envp[1];	envp[1] = buf; 	old_argv0 = argv[0];	argv[0] = argv0; 	ksft_print_msg("Check execveat(AT_EMPTY_PATH)'s comm is %s\n",		       expected);	ret = check_execveat_invoked_rc(fd, "", AT_EMPTY_PATH, 0, 0); 	envp[1] = old_env;	argv[0] = old_argv0; 	return ret;} static int run_tests(void){	int fail = 0;	char *fullname = realpath("execveat", NULL);	char *fullname_script = realpath("script", NULL);	char *fullname_symlink = concat(fullname, ".symlink");	int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);	int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",					       O_DIRECTORY|O_RDONLY);	int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);	int root_dfd = open_or_die("/", O_DIRECTORY|O_RDONLY);	int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);	int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);	int fd = open_or_die("execveat", O_RDONLY);	int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);	int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);	int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);	int fd_denatured_path = open_or_die("execveat.denatured",					    O_RDONLY|O_PATH);	int fd_script = open_or_die("script", O_RDONLY);	int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);	int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",					    O_RDONLY|O_PATH);	int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);	int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);	int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC); 	/* Check if we have execveat at all, and bail early if not */	errno = 0;	execveat_(-1, NULL, NULL, NULL, 0);	if (errno == ENOSYS) {		ksft_exit_skip(			"ENOSYS calling execveat - no kernel support?\n");	} 	/* Change file position to confirm it doesn't affect anything */	lseek(fd, 10, SEEK_SET); 	/* Normal executable file: */	/*   dfd + path */	fail += check_execveat(subdir_dfd, "../execveat", 0);	fail += check_execveat(dot_dfd, "execveat", 0);	fail += check_execveat(dot_dfd_path, "execveat", 0);	/*   absolute path */	fail += check_execveat(AT_FDCWD, fullname, 0);	/*   absolute path with nonsense dfd */	fail += check_execveat(99, fullname, 0);	/*   fd + no path */	fail += check_execveat(fd, "", AT_EMPTY_PATH);	/*   O_CLOEXEC fd + no path */	fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);	/*   O_PATH fd */	fail += check_execveat(fd_path, "", AT_EMPTY_PATH); 	/* Mess with executable file that's already open: */	/*   fd + no path to a file that's been renamed */	rename("execveat.ephemeral", "execveat.moved");	fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);	/*   fd + no path to a file that's been deleted */	unlink("execveat.moved"); /* remove the file now fd open */	fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH); 	/* Mess with executable file that's already open with O_PATH */	/*   fd + no path to a file that's been deleted */	unlink("execveat.path.ephemeral");	fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH); 	/* Invalid argument failures */	fail += check_execveat_fail(fd, "", 0, ENOENT);	fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT); 	/* Symlink to executable file: */	/*   dfd + path */	fail += check_execveat(dot_dfd, "execveat.symlink", 0);	fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);	/*   absolute path */	fail += check_execveat(AT_FDCWD, fullname_symlink, 0);	/*   fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */	fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);	fail += check_execveat(fd_symlink, "",			       AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW); 	/* Symlink fails when AT_SYMLINK_NOFOLLOW set: */	/*   dfd + path */	fail += check_execveat_fail(dot_dfd, "execveat.symlink",				    AT_SYMLINK_NOFOLLOW, ELOOP);	fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",				    AT_SYMLINK_NOFOLLOW, ELOOP);	/*   absolute path */	fail += check_execveat_fail(AT_FDCWD, fullname_symlink,				    AT_SYMLINK_NOFOLLOW, ELOOP); 	/*  Non-regular file failure */	fail += check_execveat_fail(dot_dfd, "pipe", 0, EACCES);	unlink("pipe"); 	/* Shell script wrapping executable file: */	/*   dfd + path */	fail += check_execveat(subdir_dfd, "../script", 0);	fail += check_execveat(dot_dfd, "script", 0);	fail += check_execveat(dot_dfd_path, "script", 0);	/*   absolute path */	fail += check_execveat(AT_FDCWD, fullname_script, 0);	/*   fd + no path */	fail += check_execveat(fd_script, "", AT_EMPTY_PATH);	fail += check_execveat(fd_script, "",			       AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);	/*   O_CLOEXEC fd fails for a script (as script file inaccessible) */	fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,				    ENOENT);	fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT); 	/* Mess with script file that's already open: */	/*   fd + no path to a file that's been renamed */	rename("script.ephemeral", "script.moved");	fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);	/*   fd + no path to a file that's been deleted */	unlink("script.moved"); /* remove the file while fd open */	fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH); 	/* Rename a subdirectory in the path: */	rename("subdir.ephemeral", "subdir.moved");	fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);	fail += check_execveat(subdir_dfd_ephemeral, "script", 0);	/* Remove the subdir and its contents */	unlink("subdir.moved/script");	unlink("subdir.moved");	/* Shell loads via deleted subdir OK because name starts with .. */	fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);	fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT); 	/* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */	fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);	/* Invalid path => ENOENT */	fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);	fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);	fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);	/* Attempt to execute directory => EACCES */	fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);	/* Attempt to execute non-executable => EACCES */	fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);	fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);	fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,				    EACCES);	/* Attempt to execute nonsense FD => EBADF */	fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);	fail += check_execveat_fail(99, "execveat", 0, EBADF);	/* Attempt to execute relative to non-directory => ENOTDIR */	fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR); 	fail += check_execveat_pathmax(root_dfd, "execveat", 0);	fail += check_execveat_pathmax(root_dfd, "script", 1); 	/* /proc/pid/comm gives filename by default */	fail += check_execveat_comm(fd, "sentinel", "execveat");	/* /proc/pid/comm gives argv[0] when invoked via link */	fail += check_execveat_comm(fd_symlink, "sentinel", "execveat");	/* /proc/pid/comm gives filename if NULL is passed */	fail += check_execveat_comm(fd, NULL, "execveat"); 	return fail;} static void prerequisites(void){	int fd;	const char *script = "#!/bin/bash\nexit $*\n"; 	/* Create ephemeral copies of files */	exe_cp("execveat", "execveat.ephemeral");	exe_cp("execveat", "execveat.path.ephemeral");	exe_cp("script", "script.ephemeral");	mkdir("subdir.ephemeral", 0755); 	fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);	write(fd, script, strlen(script));	close(fd); 	mkfifo("pipe", 0755);} int main(int argc, char **argv){	int ii;	int rc;	const char *verbose = getenv("VERBOSE");	const char *check_comm = getenv(CHECK_COMM); 	if (argc >= 2 || check_comm) {		/*		 * If we are invoked with an argument, or no arguments but a		 * command to check, don't run tests.		 */		const char *in_test = getenv("IN_TEST"); 		if (verbose) {			ksft_print_msg("invoked with:\n");			for (ii = 0; ii < argc; ii++)				ksft_print_msg("\t[%d]='%s\n'", ii, argv[ii]);		} 		/* If the tests wanted us to check the command, do so. */		if (check_comm) {			/* TASK_COMM_LEN == 16 */			char buf[32];			int fd, ret; 			fd = open("/proc/self/comm", O_RDONLY);			if (fd < 0) {				ksft_perror("open() comm failed");				exit(1);			} 			ret = read(fd, buf, sizeof(buf));			if (ret < 0) {				ksft_perror("read() comm failed");				close(fd);				exit(1);			}			close(fd); 			// trim off the \n			buf[ret-1] = 0; 			if (strcmp(buf, check_comm)) {				ksft_print_msg("bad comm, got: %s expected: %s\n",					       buf, check_comm);				exit(1);			} 			exit(0);		} 		/* Check expected environment transferred. */		if (!in_test || strcmp(in_test, "yes") != 0) {			ksft_print_msg("no IN_TEST=yes in env\n");

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